1. Field of the Invention
The present invention relates to a method for manufacturing an electroluminescent element including an electroluminescent layer between a pair of electrodes.
2. Related Art
An electroluminescent element includes an electroluminescent layer interposed between a pair of electrodes (anode and cathode). The emission mechanism is as follows. Upon applying a voltage between the pair of electrodes, holes injected from the anode and electrons injected from the cathode are recombined with each other at luminescent centers within the electroluminescent layer to lead to formation of molecular excitons, and the molecular excitons return to the ground state while radiating energy to emit photon.
An electroluminescent layer in the electroluminescent element can be formed by a low molecular weight material or a high molecular weight material by vapor deposition (including vacuum vapor deposition), spin coating, ink jetting, dipping, electrolytic polymerization, or the like.
These methods are appropriately selected depending on properties of materials or a shape of a film. For example, electrolytic polymerization is used to pattern form a film formed by high molecular weight materials. (For example, refer to Japanese Unexamined Patent Publication No. 9-97679.)
However, sufficient planarity of a deposited film is not available through the conventional electrolytic polymerization at present.
By the fact that an electroluminescent layer used for an electroluminescent element is formed to have a thickness of approximately from 1 to 100 nm, the planarity of the deposited film influences device characteristics of an electroluminescent element such as luminescence properties or lifetime.